Wear Behavior of Fiber Laser Textured TiN Coatings in a Heavy Loaded Sliding Regime

In heavy loaded mating components, such as sliders and sliding bearings, guaranteeing the efficiency of lubricant films for long times during severe service conditions is very complicated. In this work, the benefits deriving from the use of fiber laser sources for surface texturing of very thin TiN coatings in severe wear working conditions were demonstrated. Evaluations of the laser textured dimples shape, geometry and density are given. Wear performance of the fiber laser textured surfaces was evaluated in discontinuous oil lubricated conditions with a flat contact. High normal load and low sliding speed were applied. Comparison tests were also performed on commercial TiN and WC/C coatings. In terms of average wear volume and maximum wear depth, Laser Surface Texturing of TiN provided respectively a 70% and a 45% reduction if compared to plain TiN. If compared to WC/C the wear resistance gains were lower but LST TiN maintained such benefits for longer wear runs. SEM analysis also revealed that the laser interaction provided a localized thermal cracking to the TiN coating. However, the sliding action caused very limited and localized coating fragmentation or delamination.     

Treatment of tumors involving the optic nerves and chiasm

An approach toward treatment of tumors involving the optic apparatus is presented. When tumors cause mass effect, microsurgical excision or debulking is generally recommended. Radiosurgery has been controversial yet advances in imaging and high speed computer planning allow treatment of lesions involving the optic apparatus with low morbidity. Microsurgical and radiosurgical approaches to tumors involving the globe, orbit, suprasellar region and third ventricle are discussed. Gamma Knife radiosurgery for choroidal melanomas spares orbital excenteration. We have used a marginal dose of 20–25 Gy for choroidal melanomas and generally limit the optic nerves and chiasm to less than 10 Gy in other cases. The effective dose for cavernous hemangiomas remains unclear, however we have had success with marginal doses in the range of 16–20Gy. Lower doses may prove successful yet better spare vision in cases where vision is useful. Our combined microsurgical and radiosurgical approach to tumors involving the apparatus has had an excellent rate of sparing vision, a low overall morbidity and excellent success.     

Assessing impact of differential symptom functioning on post‐traumatic stress disorder (PTSD) diagnosis

This article explores the generalizability of the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM‐IV) diagnostic criteria for post‐traumatic stress disorder (PTSD) to various subpopulations. Besides identifying the differential symptom functioning (also referred to as differential item functioning [DIF]) related to various background variables such as gender, marital status and educational level, this study emphasizes the importance of evaluating the impact of DIF on population inferences as made in health surveys and clinical trials, and on the diagnosis of individual patients. Using a sample from the National Comorbidity Study‐Replication (NCS‐R), four symptoms for gender, one symptom for marital status, and three symptoms for educational level were significantly flagged as DIF, but their impact on diagnosis was fairly small. We conclude that the DSM‐IV diagnostic criteria for PTSD do not produce substantially biased results in the investigated subpopulations, and there should be few reservations regarding their use. Further, although the impact of DIF (i.e. the influence of differential symptom functioning on diagnostic results) was found to be quite small in the current study, we recommend that diagnosticians always perform a DIF analysis of various subpopulations using the methodology presented here to ensure the diagnostic criteria is valid in their own studies. Copyright © 2014 John Wiley & Sons, Ltd.     

猪降主动脉环向力学性质的实验研究

目的研究猪降主动脉的力学特性。方法猪降主动脉按照距心脏距离分成5组,各组由左右两侧组织、腹侧面组织构成。使用单轴拉伸方法拉伸组织,获得应力与伸张比曲线。采用经典数学模型分析5个部位(位置1～5)弹性、胶原纤维模量以及胶原纤维激活参数等特征,并对比腹侧面与两侧组织之间的力学差异。结果在环向上,胶原纤维模量随着远离心脏的方向逐渐增长,而弹性纤维模量位置1～4随着距心脏的距离增加而逐渐增大,位置5的弹性纤维模量减小,且位置5两侧的环向弹性纤维模量小于腹侧面约19%;在轴向上,弹性纤维模量小于腹侧面约37%,位置5腹侧面的弹性纤维模量相比于位置4差异不大(均值差异约5%)。在整个降主动脉中,侧面环向胶原纤维模量大于腹侧面约26%,环向弹性纤维模量在靠近心脏的四部分侧面高于腹侧面约16%。结论猪胸主动脉的环向力学特性和位置有关,最远端的部分在低应力下表现出较软特点。研究结果有助于科研人员更好理解主动脉的力学特征以及开展更细致的计算机建模。     

Effects of cartilage impact with and without fracture on chondrocyte viability and the release of inflammatory markers

Post‐traumatic arthritis (PTA) frequently develops after intra‐articular fracture of weight bearing joints. Loss of cartilage viability and post‐injury inflammation have both been implicated as possible contributing factors to PTA progression. To further investigate chondrocyte response to impact and fracture, we developed a blunt impact model applying 70%, 80%, or 90% surface‐to‐surface compressive strain with or without induction of an articular fracture in a cartilage explant model. Following mechanical loading, chondrocyte viability, and apoptosis were assessed. Culture media were evaluated for the release of double‐stranded DNA (dsDNA) and immunostimulatory activity via nuclear factor kappa B (NF‐κB) activity in Toll‐like receptor (TLR) ‐expressing Ramos‐Blue reporter cells. High compressive strains, with or without articular fracture, resulted in significantly reduced chondrocyte viability. Blunt impact at 70% strain induced a loss in viability over time through a combination of apoptosis and necrosis, whereas blunt impact above 80% strain caused predominantly necrosis. In the fracture model, a high level of primarily necrotic chondrocyte death occurred along the fracture edges. At sites away from the fracture, viability was not significantly different than controls. Interestingly, both dsDNA release and NF‐κB activity in Ramos‐Blue cells increased with blunt impact, but was only significantly increased in the media from fractured cores. This study indicates that the mechanism of trauma determines the type of chondrocyte death and the potential for post‐injury inflammation. (c) 2013 Orthopaedic Research Society Published by Wiley Periodicals, Inc. J Orthop Res 31:1283–1292, 2013     

Comparative study of awake endotracheal intubation with Glidescope video laryngoscope versus flexible fiber optic bronchoscope in patients with traumatic cervical spine injury

BackgroundThe Gldiescope video laryngoscope (GVL) as a recent intubating device has gained much popularity in difficult intubation over the last decade. It can be used as a substitute to flexible fiber optic bronchoscope (FOB) in intubating challenges. The object of this study is to compare the utility of GVL and FOB for intubating time, attempts, effects on hemodynamics, adverse effects, patient satisfaction and post intubation neurological outcome during awake intubation in traumatic cervical spine injury.MethodsFifty patients undergoing post traumatic cervical spine fixation under general anesthesia were randomly allocated to two groups in a prospective, controlled non-blinded study. All patients were premedicated with glycopyrrolate 0.2 mg iv and midazolam 1 mg iv that be repeated up to 0.05 mg/kg followed with a bolus dose of remifentanil 1.5 μg/kg then a continuous remifentanil infusion of 0.15 μg/kg/min for 3 min before procedure. Each patient underwent a wake endotracheal intubation with either GVL (G group) or FOB (F group) with manual in line stabilization (MILS). Intubating time, intubating attempts, hear rate (HR), mean arterial pressure (MAP), oxygen desaturation (SO₂ < 90%), sore throat, patient satisfaction and postintubation neurological outcome were recorded.ResultsIntubating time was significantly lower in G group compared with F group (26 ± 5 versus 72 ± 11 respectively), while the percentage of the first successful intubating attempt was insignificantly higher in G group (88%) than in F group (72%). Both HR and MAP were significantly increased only in F group during intubation in comparison with the basal line values. Both devices were safe for post neurological outcome. No significant differences of adverse effects or patient satisfaction were recorded between groups.ConclusionThe GVL is a safe surrogate for FOB during awake intubation for post traumatic cervical spine fixation.     

预成纤维桩应用于冠改向修复的初步研究

将80颗人离体牙模拟不同种倾斜角度（舌侧倾斜30°、15°，颊侧倾斜15°、30°，无倾斜）配伍分10组（n ＝8），实验组采用预成纤维桩修复，对照组采用钴铬合金铸造桩修复，各组均行铸造金属冠修复。电子万能试验机测试各组抗折载荷。结果显示修复倾斜牙时，纤维桩与铸造桩修复体之间抗折载荷无统计学差异。2种桩修复体受力过载时，主要为不可修复性折裂。根管桩种类与改向角度之间的交互作用没有统计学意义（P ＞0．05），即根管桩种类与改向角度均不会改变对方对抗折载荷的影响。